Non-aqueous Li-air batteries have a high theoretical gravimetric energy density compared to conventional Li-ion batteries, and thus have the potential for making long-range electric vehicles a reality. Reversible non-aqueous Li-air batteries use a lithium metal anode, a liquid organic electrolyte, and a carbon-supported metal-based catalyst air cathode. Li-air cells differ from conventional battery systems such as lead-acid, nickel-metal hydride, and lithium-ion systems, because oxygen is supplied as a fuel to the cell during discharge. In this case, the lithium anode releases an electron to the external circuit producing lithium ions in the electrolyte, whereas the oxygen is reduced at a cathode surface to form lithium peroxide (Li2O2) or, possibly, lithium oxide (Li2O) products.
Two major problems that have limited the successful development of Li-air batteries. First, there are difficulties in attaining full reversibility, which therefore limits cyclability of the battery. Second, low charge overpotentials limit the electrical energy efficiency of the battery.